Jet ignition for current converters



April 2, 1963 P. SCHNEIDER 3,084,272

JET IGNITION FOR CURRENT CONVERTERS Filed March 1. 1960 INVENTOR Raul (Sc/made)" BY W JWYQ Pa e ATTQRNEYS United States Patent JET IGNITION FOR CURRENT CGNVERTERS Paul Schneider, Turgi, Switzerland, assignor to Aktiengesellsclzaft Brown, Boveri & Cie, Baden, Switzerland,

a joint-stock company Filed Mar. 1, 1960, Ser. No. 12,179 Claims priority, application Switzerland Mar. 4, 1959 6 Claims. (Cl. 313152) The invention concerns ignition devices for mercury vapour current converters which by magnetic actuation of an iron core splash the mercury from the cathode to an ignition anode arranged above the surface of the mercury.

Arrangements for this purpose are known which op erate magnetically. With these an armature or core is retracted by means of a magnetic coil. This core then presses against a mercury column which is in communication with the mercury at the cathode and thus splashes mercury away from the cathode which is brought into contact with an ignition anode. For this purpose the core is located in a tube which is rigidly fixed to the easing of the converter, the end of the tube being provided with a nozzle. The core forces the mercury through the tube to the nozzle where it is ejected. When the mercury flows back, the core is returned to its initial position. Since the density of the iron core is less than that of the mercury the core is buoyed by and floats on the mercury when it is out of operation. The core has therefore to be pulled downwards by the magnet. In order for the mercury to be ejected in the upward direction, it is necessary for the tube to be U shaped, whereby the magnet with the core is located at one end and the nozzle at the other end.

It is also possible to have an arrangement where the tube with the nozzle dips into a vessel containing mercury on which a magnet core floats. The mercury is then pressed from the vessel into the tube. Here also the tube and the vessel with the core are joined rigidly to the converter casing. The disadvantage of this arrangement is that due to the impact of the core, mechanical forces can be transmitted to the converter casing and as a result leaks may occur which in time may affect the vacuum in the current converter.

In accordance with the invention it is therefore proposed to provide an auxiliary casing in which the iron core is located and that this auxiliary casing should also float in the mercury and have openings through which the mercury is forced into a further chamber in communication with the nozzle, the wall of this chamber being rigidly connected to the casing of the current converter.

A constructional example is shown in FIG. 1. Reference number 1 indicates the current converter casing in which the mercury 2 in the form of a pool forms the cathode. The ignition anode 3 lies above the mercury cathode pool. Depending from the bottom of easing 1 is a tubular extension 1a in the form of a separate part which is secured to the main casing 1 at the points 11. Surrounding the tubular extension 1a is a magnet coil 5 which is adapted to be energized from a suitable source of current whenever it is desired to ignite the converter. The interior of the tubular extension 1a forms a well or chamber below the main mercury pool 2 and within which mercury from pool 2 collects and fills the same, the mercury entering the chamber 10 through a nozzle 4 located at the upper end of the tubular extension 1a and directly beneath the ignition anode 3. Arranged to float within the mercury filled chamber 10 is a tubular casing 7 which is'open at the bottom and closed at the top except for a small bore vertical discharge open- 3,084,272 Patented Apr. 2, 19$3 "Ice ing 12 which establishes a communication between the interior and exterior of casing 7. The top of casing 7 bears against a depending stop pin 8 which is adjustable in effective length and acts as a stop for the casing 7 so as to space the top of the latter from the top of chamber 10 and hence from the entrance to nozzle 4. Cas ing 7 serves as a floating cylinder for an iron core .piston 6 disposed therein and which latter constitutes an armature element which is pulled down within cylinder 7 whenever coil 5 is energized. It will be seen from the drawing, that the external diameter of cylinder 7 is less than the diameter of chamber 10 so that cylinder 7 as it floats in the mercury is free to move in all directions. Located in the lower part of cylinder 7 are a plurality of openings 9 extending laterally through the Wall thereof. These openings 9 lie so high above the floor of chamber 10 that the mercury remaining below these openings as armature piston 6 is pulled downward serves to dampen movement of the piston.

When it is desired to ignite the converter, magnet coil 5 is energized. This causes the armature piston 6 to be pulled down within cylinder 7 to thus force the mercury within cylinder 7 outwardly through openings 9 into chamber 10 and hence force mercury upward and outwardly from chamber 10 through nozzle 4 at considerable velocity thus causing mercury to be squirted onto the ignition anode 3. The magnet coil 5 can then be deenergized whereupon the armature piston 6 rises once again within cylinder 7 to the initial position shown in the drawing and presses out through the aperture 12 any mercury which may have collected between the upper end of piston 6 and top of cylinder 7, the piston coming to rest against the top of cylinder 7.

The entire arrangement serves the purpose of preventing impacts from the core 6 being transmitted to the casing 1. Since the cylinder 7 actually floats in the mercury it can readily move in all directions and is therefore resilient as regards impacts without any par-ts connected to the casing 1 being touched. The lower mercury sump prevents any impacts reaching the floor.

The tightness of the. entire arrangement is not influenced or affected by the operation of the ignition device.

I claim:

1. In a jet ignition device for mercury arc converters of the type including a mercury pool type cathode and an ignition anode, the combination comprising a housing arranged below the mercury pool and ignition anode, said housing establishing therein a mercury filled chamber, an electrornagnet coil surrounding said housing and chamber, a nozzle disposed at the upper end of said chamber, the discharge outlet from said nozzle being located in said mercury pool beneath said ignition anode, a casing disposed within said chamber and spaced from the walls of said housing defining said chamber so as to be freefloating in the mercury contained Within the same, the lower portion of said casing including at least one discharge opening to said chamber, and an iron core arranged as a piston within said casing above said discharge opening whereby said core will be pulled downwardly within said casing upon energization of said electrornagnet coil to force mercury from within said casing outwardly through said discharge opening into said chamber and thereby force mercury from the upper end of said chamber through said nozzle.

2. A jet ignition device as defined in claim 1 for mercury arc converters wherein said discharge opening at the lower portion of said casing is arranged laterally through the casing wall and at such a height that the part of the mercury below said opening serves to dampen further downward movement of said core.

further includes a stop pin disposed within said chamber 5 at the upper end thereof said pin constituting a stop for the upper end of said casing and said iron core within the sarne when said eleetromagnet coil is not energized.

5. A jet ignition device as defined in claim 4 wherein said stop pin is adjustable as regards its efiective length 10 to thereby effect an adjustment in the damping action.

' 4 6. A jet ignition device as defined in claim 1 and wherein .the upper end Wall of said casing includes an aperture therethrough communicating with said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,781,330 Jonas Nov. ll, 1930 2,102,956 Hurlimann Dec. 21, 19 37 FOREIGN PATENTS 817,505 Great Britain July 29, 1959 

1. IN A JET IGNITION DEVICE FOR MERCURY ARC CONVERTERS OF THE TYPE INCLUDING A MERCURY POOL TYPE CATHODE AND AN IGNITION ANODE, THE COMBINATION COMPRISING A HOUSING ARRANGED BELOW THE MERCURY POOL AND IGNITION ANODE, SAID HOUSING ESTABLISHING THEREIN A MERCURY FILLED CHAMBER, AN ELECTROMAGNET COIL SURROUNDING SAID HOUSING AND CHAMBER, A NOZZLE DISPOSED AT THE UPPER END OF SAID CHAMBER, THE DISCHARGE OUTLET FROM SAID NOZZLE BEING LOCATED IN SAID MERCURY POOL BENEATH SAID IGNITION ANODE, A CASING DISPOSED WITHIN SAID CHAMBER AND SPACED FROM THE WALLS OF SAID HOUSING DEFINING SAID CHAMBER SO AS TO BE FREEFLOATING IN THE MERCURY CONTAINED WITHIN THE SAME, THE LOWER PORTION OF SAID CASING INCLUDING AT LEAST ONE DISCHARGE OPENING TO SAID CHAMBER, AND AN IRON CORE AR- 